Dental matrix instrument



L. H. DVORAK I 2,647,315

DENTAL MATRIX INSTRUMENT Filed May 18, I950 Patented Aug. 4, 1953 UNITED STATES PATENT OFFICE 15 Claims.

My invention relates to dental matrix instruments and particularly to an improved dental matrix band, and to improved apparatus for positioning, adjusting and retaining a dental matrix band.

A general object of my invention is to provide an improved dental matrix and improved matrix positioning, adjusting and retaining means.

Another object of my invention is to provide a dental matrix, together with matrix band positioning and adjusting means, which permits the positioning of the operative, filling-retaining portion of the matrix band in close and conforming relation to the cavitied portion of a tooth.

A more specific object of my invention is to provide devices which, in use, cause a matrix band to conform to and lie closely against a surface of a tooth, from the occlusal edge of the tooth to the gingival line.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further objections and advantages thereof, may'best be understood by reference to the following description taken in connection with the accompanying drawing, in which Fig. l is a top view of an instrument in. accord with my invention, shown in operative association with a tooth to be filled; Fig. 2 is a side view of a portion of the instrument in position as in Fig. 1; Fig. 3 is a view of the side of a portion of the instrument opposite to the side shown in Fig. 2; Figs. 4 and 5 are sectional views taken along lines 4-4 and 5-5, respectively, of Fig. 1; Fig. 6 is an exploded perspective view showing in more detail certain parts of the instrument of Fig. 1; Fig. 7 is a top view of a portion of the instrument showing a modificatio-n in accord with my invention; and Fig. 8 is a perspective view of another part of the instrument in accord with a further modification.

Referring now to the drawing, the instrument is shown in Fig. 1 in position in association with two proximal molars l and 2. The cavity 3 in molar I is covered along the side of the tooth, by an operative portion of matrix band 4. The opposite end portions 5 and 6 of band 4 are attached to respective band-and-holding members i and 8 by wrapping the ends of the band about a portion of each member and by thereafter sliding a sleeve or cap over the member to lock the ends to the holding members as hereinafter described. The members l and 8 are internally bored and threaded and are diSpQed on a threaded rod 9- in a manner such that by rotating the rod 9 in one direction the members 1 and 8, and the opposite band ends 5 and 6, are separated, and by rotation in the other direction, are drawn toward each other.

A rigid or semi-rigid clip or stiffening member I0 is disposed on an intermediate or central portion of the matrix band 4 and is so proportioned and arranged as not to pass through the interstice between teeth I and 2, and also to cause the band to lie against exposed sides or faces of the proximal teeth at opposite ends of the clip I ll. The specific construction of clip I0 is further described in connection with Fig. 6, and a modified construction is shown in Fig. 8.

The members I and 8, which hold the respective ends of matrix band 4, and which are movable apart or together by appropriate rotation of the double threaded bolt or rod 9, are each provided with two protruding portions in the form of ears, the ears of member 1 being desi nated II and I2 and those of member 8 being designated 13 and I4. These ear are arranged to guide or press the matrix band 4 into conforming contact with the teeth as hereinafter further explained.

The matrix band 4 extends through the clip In and, from the left hand end of the clip as seen in Fig. 1, passes along and firmly engages substantially the whole side surface of tooth l which confronts tooth 2. This operative portion of the matrix band passes between tooth l and ear H, and the end or terminal portion 5 of the band is passed through a central portion of the movable member 1 and finally bent back to be locked on member I, a cap I5 being provided to slip over a part of member I more securely to maintain the attachment of end 5 to member 1.

The portion of matrix band 4 which extends from the right hand en of the clip 10, as seen in Fig. 1, passes along the side of tooth 2 which confronts tooth l and between tooth 2 and ear iii of member 8, the end portion 6 of the band being attached to member 8 and held in position thereon by a cap 16, all in the manner heretofore described in connection with end portion 5 and member 1. Of course, this portion of the band in contact with tooth 2 is in operative position for use in filling a cavity, if one exists, in tooth 2 along the side confronting tooth I.

Threaded rod 9 is provided at one end with an upset portion or rounded knob I! which prevents member 1 from becoming inadvertently completely unscrewed from the rod, and it may also prevent the removal from the rod of cap l5 under 3 certain circumstances. The rounded end further serves to minimize the chance of damage to the mouth of the patient.

At the other end of the rod a knurled knob I8 is provided to permit rotation of the rod by the fingers. A sleeve 19 is shown on the rod between member 8 and knob l8. This sleeve may be loose on the rod or may be tight fitting, as desired. Ifloose fitting, the sleeve may beggrasped by the fingers of one hand to hold the instrument in position while the knob I8 is being turned by the fingers of the other to adjust the separation of members 7 and 8. The ll'lStl-UHIGIIGHHHYbfi controlled without difdculty, however, even though sleeve 19 is entirely omittedyin which'case' rod 9 may be either threaded :throughoutxits lengthor maybe smoothand unthreadedthroughout the portion, approximately, shown covered by the sleeve IS in Fig. 1. It has been found desirable to prevent cotton from becoming tangled .in. the threads of the rod to attach the sleeveflfl -to-the cap I5, thereby to leaveexposed :the threaded portion adjacent knob 18 whichis .re-

mote from the area in which cotton. is1normally used. 'It may be also. desirable-tov attach a. sleeve, similar tosbut shorter than sleeve 19; tozcap ($5 to extend over knob 17 and to cover the threads 'along the portion of the rod between .holding -member I and knob i1. If sleeves-attached to caps l5 and i6 are so provided to cover :the .threadsadjacent the tooth or teeth being. filled, the-sleeves may be pulled by the fingers :to slide the caps. ofi of members I and 3 when'itis' desired to change orv adjust the matrixband as held by members I and 3.

Fig.2 is a side View of the instrument in posiwtionon teeth I. and 2 as in Fig; .l and shows Lthe relationship between the clip 'ldandxteetlr Land 52. The lower edge of clip I lies close toror along --the-:gingival line i9 and the top: edgeof theaclip is at about the level of the occlusal surfaces-of the "teeth. The matrix band which: extends through clip i0 is of slightly less'widthfthan the clipgthezwidth'of the band beingmeasuredxin the direction from top to bottomaof the toothas ISI IQWILYBJId it willbe seen that: neither theclip 'l-IIOI' matrix band will interfere withnormalclosing of the jaw with the matrix band and: clip in .the position shown.

Theyiew of the instrument infFiguS is-taken .-from= the side opposite the teeth and. clearly .'.shows ears i2 and M of members I and 8,- respectively. 'It is. to be noted that theslot between aearall and the adjacent edge of cap :lS-of meml':b81=".1 is inclined from the vertical, as istthe slot between car i and cap 16 of member: 8. The

inclination in each instance is such theta-matrix .band having end portions extending, respectively, uthrough these slots and locked in place under soaps l .and IE will be soheldas to have the lower edges of the opposed portions-of vthesband adjacent the respective ears [2 and. I l" further ::apart than. the upper edges. The cars: l|:..and -'l3, shown in other figures, and the slots formed between these ears and caps l5 and [6,respecz'tively, are similarly inclined.

Accordingly, whether the matrix bandisrposi- 'rtioned onthe. one side of the instrumentrforuse on teeth of the lower left jaw as shown in Fig.1 1 IOIfOII the other side for use on teethofthe lower :'.rightjaw, that edge of the matrixband which is -toward the gingival line will be'pulledinto engagement-with the divergentsurfaces of the ad- :jacent teeth near thegingival line. ':This;desired result is obtained by the foreshortening efiect or the divergently inclined slots formed by cars H and I3, or 12 and M, depending on the side of the instrument on which the matrix band m positioned, and by the trapezoidal shape of the clip 5 I0 as seen in Fig. 2.

It will be apparent that certain portions of the instrument which are seen in several figures have been similarly numbered in each instance, andit'is unnecessary to repeat a description therelO of for each'figure. Thus, for example, it is to be understood that the hereinabove descriptions of "rod 9, knob l1 and sleeve 19 apply to the view of Utheuinstrument as seen in Fig. 3 in the same manner as to the views of Figs. 1 and 2.

lurning now to Fig. 4, which is a partially sectionalyiew-taken along line 6- 3 of Fig. l, the band 4 is seen to lie closely against the face Of- -to'dth I to form a wall across the cavity 3. The member I is shown in end view and com- 20 prises? ears --,I I. and 12 and legs as and 2|. "End .ipontionwS .of matrix [band i is inserted behind earr l lazandrextends along the inner face otleg :im-rtorbefolded back at the far end being taken as that toward rod 9 and the outer face being thatltoward tooth-l. Cap (5 is in position to :maintai-n the-extreme end of portion 5 against the outer face, thereby to lock the end of the bandctctmember I. It is to be noted that car .l |.-.is:-so.-.shapedas to press the edge of band 4 -which-liesnear the gingival line against the surjace-of'theitooth 5. Since teeth are smaller near thesgingival line thanat the occluding surface, ear tie-extends from the bottom of member towardtlzietoothand is then bent upwardly and ;sl;ightlyrbackwardlytoward the center of member .1. Thecnrve. of the upwardly extending por- .tion. of-ear H :issuch as to conform as nearly as practicable to the shape of the tooth. The

-material of which member I is made is prefer- 40 .ably.sli htlyresilient-and is deformable by pliers .--.to.taheia -"permanent set. Thus the cars, such "as card-.Lu-may bebent by pliers into substan- --tially the-correct configuration, and the resilience wi-llgzpermit.the-ears thereafter to tend to adjust 5 themselves toexactly the proper shape when the wbandds in placeandtightened against the teeth. 1 Clip: Hi, asshown partially in cross section in .Fig: 4, comprises a central portion 22, a folded- .cver top portion 23-and an upturned ear portion 5 .24. The matrix band passes between portions "22 and 23, and the arrangement is such as to holdclip- .Hlfirmly to band inand thereby to pro- -=vide admatrix band having a portion approxi- .:mately midwaydbetween the ends of increased -bll'1k;.'StiffflBS-S:Or rigidity, this-portion correspondingrtoithe-part crimped between the folded porzftions-lz and 23 of the clip it. It may prove dessirable under-some circumstancesmore firmly to attachxclip [Bi-1705116 intermediate portion of band -s4;-by Ithe-use-of solder or cement or in other known :ways, and it is also practical to construct the matrix band of a single piece of metal with an .rintermediateportion of greater rigidity, or less .i'fleXibilitYJthereby to conform to the character- :istic utilized -in my invention.

'The functions of the intermediate portion of in- ;creased rigidity of the matrix band are. first, to rkeep thisportion of the band from being pulled :through the interstice between adjacent teeth, -:-1S.l1h': 31S |='-.a1HdZiILFig. l, and secondly, to assist, -.-by the preferred trapezoidal shape of the portion -:of increased rigidity, in the foreshortening of the 'ibandaalong the edge to be. disposed adjacent the gingival li-ne. The tolded-eover portion 23 may be thought of as merely adding to the band at its intermediate portion sufficient bulk to prevent the intermediate portion from being pulled through the interstice between teeth I and 2. It may be thought of, alternatively, as a separate member interposed between the intermediate portion of the band and the interstice having a bulk suflicient to maintain the intermediate portion from pulling through the interstice. It may also be thought of as being a part of the band to make the band stiff through a length great enough to bridge the interstice, or it may be considered as a separate member attached to the band and being characterized by sufficient stiffness and length not to pass through the interstice. A great many other ways of providing bull; or stiffness to perform the necessary function will be apparent to those skilled in the art.

The ear portion 24 of the clip II] is useful in further tending to maintain the band closely along the tooth face, and as heretofore explained it is preferably bent or curved to approximate the shape of the tooth. Ear portion 24 of clip I ll and ears II, I2, I3 and I4 of members I and 8 are all preferably of a somewhat ductile and resilient metal to permit bending thereof as with pliers and slight self-adjustment, because of the resilience, as the band is tightened in place. It is thus possible to obtain a close fit of the band to the teeth regardless of the shape of the teeth in any particular instance. It is to be assumed, of course, that different sizes and shapes of matrix bands and of clips will be used for the several distinct types and sizes of teeth, wider bands being used for longer teeth and longer clips for wider spaced teeth, and the like.

The instrument is shown in Fig. 5 partially in cross section taken along the line 5-45 of Fig. 1. Fig. 5 discloses additional details of the interrelation of the parts of the instrument, and particularly the manner in which matrix band 4 extends behind tooth 2 and into the end of clip I0, the clip, as heretofore explained, performing the function of providing a stiff or enlarged intermediate portion of the matrix band. The position of cap I6 on matrix band-end-holding member 8 is also readily apparent in this view. Additional reference numerals are applied to Fig. 5 to designate, for purposes of orientation, the portions of the instrument heretofore described in connection with Figs. 1 through 4, and these hereinabove descriptions are applicable to the parts of Fig. 5.

Many of the details of the instrument heretofore described are best understood by reference to the exploded view of the instrument shown in Fig. 6. It will be immediately apparent that rod 9, including knobs I1 and I8 and sleeve !9, is omitted from Fig. 6 for the sake of clarity.

As shown in this figure clip It comprises a generally rectangular sheet of metal having one end or edge out out to form ear portions 2% and 25. These ear portions are turned upwardly from the bottom edge of the clip and a flap 23 is formed by turning downwardly the upper portion of the clip. The body or outer portion 22 remains substantially vertical, and when the clip is in position on matrix band 4, the portion 22 remains on the outer face of the band while flap 23 is folded over to lie against the inner face. Ear portions 2 5 and 25, of course, extend further inwardly than flap 23.

The central or intermediate portion 26 of matrix band 4 is maintained by clip If! in straight or slightly rounded shape. The portions between this immediate portion 26 and the respective end portions 5 and 6 are adapted to extend through the interstice between a pair of proximal teeth and to conform with the confronting sides of the respective teeth in connection with which the instrument is to be used. In attaching the ma trix band to the movable members I and 8, end portion 5 is wrapped about leg 20 of member I and end portion 6 is wrapped about leg 21 of member 8. The band thus extends from a point on the outer surface of a leg 2Il, around the end of leg 20 which is remote from ear I I, along the inner side of leg 20 between the leg and the central barrel portion 28 of member I, and thence through the slot separating leg 20 and ear I I. End portion 6 is similarly wrapped about leg 27 of member 8 to extend between leg ill and the central barrel portion 29, and thence through the slot between leg 2! and ear I3. Caps I5 and I6, which are in the nature of ferrules, are slipped over the ends of members I and 8, respectively, to prevent end portions 5 and 6 from becoming unwrapped from their respective legs 2-0 and 2'! and further to lessen the danger of injury to the mouth of the patient from the sharp corners of the band-end-holding members if these members were not so covered. Each of the caps or ferrules I5 and It comprises a hollow member, which may be formed, for example, from a section of metal tubing, the metal of the tubing being preferably of stainless steel. The tubing is shaped to conform approximately to the leg portions of members I and 8, and the remote ends of the caps may be closed by a metal plate, such as the plate 30 of cap I6, through which a hole 31 may be drilled to permit the passage therethrough of the threaded actuating rod heretofore described. Caps I5 and it are proportioned substantially to cover legs 20 and 27 but to leave ears H, I2, I3 and I4 exposed. It is preferred that the ears remain exposed to press band 4 against the teeth.

It will be apparent from an inspection of the general characteristics of the instrument as disclosed in Figs. 1 and 6 that it is reversible. While Fig. 1 shows the instrument as applied to a pair of teeth in the lower left or upper right jaw section, the instrument may be easily arranged for use in connection with teeth in the lower right or upper left jaw by removing caps I5 and I 6, sliding end portions 5 and 6 upwardly off of legs 20 and 21 respectively, and by turning around matrix band 4 with clip I0 attached, in the position in which end portion 5 can be wrapped around leg 32 of member 8 and end portion 6 wrapped around leg 2| of member 1. Caps I5 and I6 should then be replaced, of course. After the matrix band is thus reversed, ears l2 and Idof members I and 8, respectively, will be effective to press matrix band 4 into proper conforming relation to teeth of the lower right or upper left jaw and ears I I and I3 will not be used.

In the foregoing discussion it is assumed that the rod 9 and holding members l and 8 are disposed on the buccal side of the teeth. This is not necessary, and it may be found desirable ing the band in position in respect to teeth more or less .slanting from the gingival line to the oceluding edges. Similarly, clip I may be substantially shorter along the top, as best seen in Fig. 2, or it maybe ofrectangular or other shapes best to suit the particular: situation.

""The' ears'24 -andZt'rofclip Id, shown in Fig. -6, are,'..like ears H, I2, !'3 and [4, preferably bendable with pliersand slightly resilient to provide an efiectivealign'ment of the matrix band along the teeth.

"Figf'lillustratesamodification of the instrument inirespect'to one of the band-end-holding members, designated generally 33, which comprisesearsl34' and35 and' legs 36 and 31', each of which is similarto and-performs the function of the respective ears and legs of members I and 8 heretofore described. Thecentral barrel portion 38 of the 'modified member 33, however, is not internallythreaded but comprises a smooth bore in which a smooth unthreaded portion 39 of rod 40 'is'free to rotate. The threaded portion of roddll carries only a right hand, or left hand, thread and a member'similar to member 8 of Fig. I is mounted thereon toapproach and to be moved away fromthe unthreaded portion 39 in response to rotation of'rod 40.

'Ro'ddfl terminates at one end in a knob or boss 41,.at or near the remote end of the smooth portion 39, andthe' barrel portion 38 of member 33 has a cut out transverse slot42 cooperating with the knob to maintain member 33 in fixed position along the rod while permitting free rotation of the rod with respectto' member 33. Turning the rod, accordingly, moves a member such as member 8 of'Fig. 1 along the rod toward or away from member-33, the. ends'of a matrix band being held by' these respective members as in Fig. 1.

A further modification'applicable to the invention is shownin'FigJS, which comprises a modified'clip 43' for use with the matrix band of Figs. 1 through 6.

In'this modificationthe .clip is formed of a single strip of metal, 'or other 'stifi material, shaped into. a flattened frustoconical configuration to impart to theintermediate portion of a matrix band, such as portion 26 of band 4 seen in'Eig. '6, when clip 13" isplaced inside this portion, approximately the same shape as that shown inEigs.-'l,l2, 4 and 5. The clip 43 .is readily removable and convenient to use first with one band and then another, without unfolding of the clip as necessary with clip H3 heretofore described. .Clip 43 is-simple in construction and is. also .adapted for soldering to the intermediate portionof. aband.

.Cuts'M. and- 45 of clip 43, near the ends thereof, separate ear portions and 4'! which may bebentlihto' the position and shape best suited .to arparticular .pair of teeth, and these ears are preferably. resilient to be, to at least a small de- .gr.ee,self-adjusting, as with the ears of the bandend-holding members and the ears of clip 30.

Clip-'43 comprises, in use, a member too large or bulky to pass through the interstice between proximal. teeth, and since it is to be located between the intermediate portion of a matrix band and such intersticc, it prevents the intermediate portion of the band from being pulled through such interstice.

In use, the instrument as shown in Figs. 1 through 6, unmodified or modified in accord with Fig. 7 or 8, is positioned with the threaded rod on one. side of the. teeth and the clip Hi, or clip 43,'on. the other, with the matrix band between the clip and'band end holding members extending through I the "interstice between the proximal teeth, of whichone is to be filled for-example. Turning the rod-moves apart the band-endholding members and separates ends 5 and 6 of the band. The resultant band tension pulls the clip tightly up against the teeth on the one side of the tooth line and the holding members against the teeth on the other. The band is thus caused to hug theteeth, not only through the interstice but for some distancealong the lingual and buccal'faces as well. The ears of the clip and of the holding-members, when properly adjusted, assist in this respect'and' tend to extend the effective coverage by the band of the side areas of the' teeth.

It will be recognized," too, that the tension of the band will tend to separate the teeth. This action is of substantial importance, for after the filling is completed,- the band may be readily removed from the wideinterstice without damage to the filling at the important occlusal edge, since the teethremain separated for a short time'after the rodis turned to-release the tension on the band.

As so used, it will be seen that the band is held against the side of atooth, such as tooth i, having a cavity, such as cavity 3, by the combined action of the enlarged'portion of the band, represented by'the clip Ill, which maintains this portion of the band against being pulled through between teeth I and 2, and of the member 7 which pulls end portion 5 of the band along the buccal face of tooth l'away from tooth 2. Tooth 2 may be thought of as an anchor against which the instrument pushes with a force determined by the tension of the band. An equal force is applied to the portion of the band contacting tooth I through clip [0- at the lingual side of tooth I and through member 7, to end portion 5, at the buccal side of toothl. The tension thus imposed on the band to force it against thatside of tooth l which faces tooth 2 permits the use ofa flexible band which is caused closely to conform to the contour of this'side of the tooth and which is thus firmly held in position to permit a filling to be pressed hard into the cavity without danger of the filling material leaking or oozing out past the retaining wall constituted by the matrix band.

While I have shown only certain preferred embodiments of'my invention by way of illustration, many modifications will occur to those skilled in the art, and I therefore wish to have it understood that I intend, in the appended claims, to cover all such modifications as fall within the'true spirit and scope of .my invention.

What I claim asnew and desire to secure by Letters Patentof the United States is:

l. A dental matrix instrument for use with a tooth comprising a side confronting a. proximal tooth separated therefrom to form an interstice, said instrument comprising a flexible matrix band positionable against said side and sufficient- 1y long to extend beyond both ends of said interstice, and means to force the extending portions of said band along the buccal and lingual sides,

respectively, of said first tooth away from said proximal tooth, said means comprising slotted band end holding means, said last means having a curved protruding portion adjacent said slot engaging said band to urge said band into conformance and engagement with said first tooth adjacent the gingival line.

2. A dental matrix instrument for use with a "tooth'compri'sing a side confronting a proximal tooth separated therefrom to form an interstice, said instrument comprising a flexible matrix band positionable against said side and sufliciently long to extend beyond both ends of said interstice, and means to force the extending portions of said band along the buccal and lingual sides, respectively, of said first tooth away from said proximal tooth, said means comprising a first member attached to one of said extending portions at one of said two last mentioned sides of said first tooth, a second member at the other of said two sides holding said other extending portion spaced from said proximal tooth, and force applying means to tension said first member away from said proximal tooth, each of said members having a portion protruding inwardly therefrom and engaging said respective extending band portions to urgesaid extending portions into hugging relation respectively with said buccal and lingual sides of said first tooth.

3. A dental matrix instrument for use with a tooth, comprising a side confronting a proximal tooth separated therefrom to form an interstice, said instrument comprising a matrix band positionable against said side and sufficiently long to extend beyond both ends of said interstice, and means to force the extending portions of said band along the buccal and lingual sides, respectively, of said first tooth away from said proximal tooth, said means comprising a first member attached to one of said extending portions at one of said two last mentioned sides, a second member at the other of said two sides holding said other extending portion spaced from said proximal tooth, adjustable force applying means to force said first member away from said proximal tooth along said one side, and band means extending through said interstice bearing on said proximal tooth to serve as an anchor for said second member and said force applying means, said band means comprising a continuous portion of said matrix band.

4. A dental matrix instrument comprising a flexible matrix band having an intermediate portion of substantially reduced flexibility and two ends, and adjustable tensioning means engaging ends adjustably to pull apart said ends, thereby to tension said band.

5. A dental matrix instrument comprising a flexible matrix band having two ends and an intermediate portion separated from said ends, stiffening means attached to said portion, and means adjustable to separate said ends.

6. A dental matrix instrument comprising a flexible matrix band adapted to extend through the interstice between proximal teeth, said band having an enlarged portion of greater thickness than the width of said interstice adapted to be disposed on one side of said proximal teeth and having an end portion to be disposed on the other side of said proximal teeth, and means to pull said end portion in the direction from said interstice along said other side of one of said proximal teeth.

7. A dental matrix instrument, comprising a flexible matrix band having two ends and an intermediate portion separated from said ends by portions adapted to extend through the interstices between a pair of proximal teeth and to lie against respective confronting side faces of said teeth, said band being adapted for the disposition of said ends on one side of the tooth line and said intermediate portion on the other side, said intermediate portion being character- 10' ized by a bulk greater in size than said interstice thereby not to pass therethrough, and adjustable tensioning means on said one side of said tooth line connected to said ends and operative to pull apart said ends and thereby to tension said band.

8. A dental matrix instrument, comprising a flexible matrix band-having two ends and an intermediate portion separated from said ends by portions adapted to extend through the interstice between a pair of proximal teeth and to lie against respective confronting side faces of said teeth, said band being adapted for the disposition of said ends on one side of the tooth line and said intermediate portion on the other side, said intermediate portion having sufficient stiffness through a length greater than the distance across said interstice to prevent said intermediate portion from passing through said interstice, and adjustable tensioning means connected to said ends and operative to pull apart said ends and thereby to tension said band.

9. A dental matrix instrument, comprising a flexible matrix band having two ends and an intermediate portion separated from said ends by portions adapted to extend through the interstice between a pair of proximal teeth and to lie against respective confronting side faces of said teeth, said band being adapted for the disposition of said ends on one side of the tooth line and said intermediate portion on the other side, adjustable tensioning means connected to said ends and operative to pull apart said ends, and means to maintain said intermediate portion on said other side of said tooth line.

10. A dental matrix instrument, comprising a matrix ban-d having two ends and an intermediate portion separated from said ends by portions adapted to extend through the interstice between a pair of proximal teeth and to lie against respective confronting side faces of said teeth, said band being adapted for the disposition of said ends on one side of the tooth line and said intermediate portion on the other side, means to separate said ends, and means to maintain said intermediate portion on said other side of said tooth line, said last means comprising a member disposed between said intermediate portion and said interstice.

11. A dental matrix instrument, comprising a matrix band having two ends and an intermediate portion separated from said ends by portions adapted to extend through the interstice between a pair of proximal teeth and to lie against respective confronting side faces of said teeth, said band being adapted for the disposition of said ends on one side of the tooth line and said intermediate portion on the other side, means to separate said ends, and means to maintain said intermediate portion on said side of said tooth line, said last means comprising a member disposed between said intermediate portion and said interstice and having a portion cooperating with said band to maintain a part of said band against a part of one of said teeth.

12. A dental matrix instrument comprising a flexible matrix band, a stiffener member engaging an intermediate portion of said band, first and second band-end-holding members detachably secured to respective ends of said band, and means comprising a threaded rod to separate said ends, at least one of said holding members comprising a threaded portion engaging the threads of said rod.

13. A dental matrix instrument comprising an elongated, .fiexibletmet llici matri abandr a i tainine imember afiixed. to, he int rme i e-p ti'onuofi; said :band. .said: membe eine pron rproximal teeth, said band having operativepgr-v tionsextending mom; said. memben and t r in i s: in-resnective end mottion remote rom said member. two .endrholdingemem rsdetachabl engaging. respectively said end portions, at least one: ofu said" members... being threaded, and threadedrmeanscooperating with said threaded member to-adiust.theseparation pt said end portions...

14; Andental' metriminstrument for-use in conneatiomwitha defeotive;.-tooth having a second pnoximal :tooth separated therefrom to define an intenstice== therebetween, said teeth defining a toothiline pnesentingsamuooal side and a ,lingual side-for. saidteetlr; said instrument comprising am elongated: flexiblematrix .band, 2;; rod threaded through at least (part- -of. its vlength and carrying t-wosband-end-ho1d-ing.Jmembers,.a -1east one of sa-idamembers bBiIlQgthllBdCiQQlwtO cooperate with thei-thireadswf.-sa.id.-rod and.ato be moved therealongrinzresponse;-to;.rotation of said rod, the othen said.- i member-. bein u prov ded; with e ns cooperating .witlzratporltion of said-rod to -prevent said other. member from following said first memb en when .saidsrod is; rotated, n i er iateqportiorr ofia said zba-nd being proportioned to presentasumoient bulk-not to. pass through said mtersticetand gbeingedapted for positioning adjanentpne .ofrsaids-idesbeyond one end of said interstice, saidsband having. two; portions extending fromjrespfictive opposite ends of said intermediateportionwhich are adapted to extend side by; sidQ; through said .interstice and which have 12 rmin t p rt on ine dia ente 5 h. aid s de. aid t ina qrt o sgb i e detachabl .connecte r ec i ely; o: said. mm ers.-.; aid ,rod, nd me bers .bein

, da ted .to efi spose e las nt ai he side-:

4 stipenlongsaidothensideof oneof said.proximal e th..- ai m an .co pri es d n o1d.- ing den-ice having. a slot toreeeive :said band, said ot heme-i cl ne wtheuv ca up rd y o Ward. said interstioe. whereby said. .band said. interstice hngs the lowen portion .of, saidone tooth adjacent the gingival line.

LEWIS H DVQRAK,

Refexzenaes Cited .the. fi1e 0f. this patent UNITED STATES PATENTS, 1

Num per I Name Date 351,955] Miller Oct.- 19 -1886 55259? Peterson Jan. '7, 1896- 766.018 Carro11' July 26; 1904 1, 8.68', 981' Ivory a July 26, 1932 2.5192526" Haas Aug.-15, 1950 2529,17; Muller Nov. 7, 1950 FOREIGN. PATENTS Number Country Date 79,728 Switzerland May 1, 1919 263519 Switzerland Aug. 31,1949

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